Laser-induced off-diagonal thermoelectric voltage in La1-xCaxMnO3 thin films

Laser induced off-diagonal thermoelectric voltages were observed in La0.67Ca0.33MnO3 thin films deposited on vicinal cut SrTiO3 substrates, as well as in films of other doping levels, The dependence of this voltage on photon fluence, illuminated length of the film, film thickness and orientation are in remarkable analogy to the results reported for YBa2Cu3O7-x thin films. That suggests an identical physical mechanism in both materials which based on the existence of off-diagonal elements in the Seebeck tensors. It demonstrates that an intrinsically anisotropic charge transport exists in these series of materials, in spite of the quasi-cubic crystal structure of the base material LaMnO3. From the results obtained on films with a systematic variation of the doping level and materials, the anisotropy of the Seebeck tensor is suggested to be a contribution of the long-range cooperative Jahn-Teller distortions. (C) 2000 Elsevier Science B.V. All rights reserved.